The present invention relates to a spinal implant system, and is suitable for use in treatments for correcting various spinal deformities. In particular, this invention relates to a spinal system of the type that includes an interpositional sleeve for securing various types of attachment devices to a spinal rod.
The use of an interpositional sleeve to secure a spinal attachment device to a rod is taught in the prior art, such as in U.S. Pat. Nos. 5,112,332 and 5,116,334 to Cozad et al. The present invention is a modification and improvement of these Cozad et al. patents, and as such these two U.S. Pat. Nos. 5,112,332 and 5,116,334, are incorporated herein by reference. Both of these Cozad et al. patents, as well as the present invention, are assigned to Zimmer, Inc. These two Cozad et al. patents are both divisional of U.S. Pat. No. 5,074,864 to Cozad et al.
These Cozad et al. patents disclose a spinal implant system which includes a tapered split sleeve having a separate, discrete lock member or lock nut securable over the sleeve. The lock member interacts with the open back attachment device by acting on an exterior surface of the attachment device to secure an interference frictional interconnection between the tapered sleeve and the attachment device to secure the device to the rod.
The following other spinal systems are known which disclose the use of an interpositional sleeve:
U.S. Pat. No. 5,010,879 to Moriya et al. discloses a spinal system having a wedge-like slit sleeve having a cylindrical body with a flange 7a on one end and a tapered portion 8a on the other end. The wedge-like member is forcibly inserted at the tapered end thereof between a spinal hook and a rod.
U.S. Pat. Nos. 4,815,453 and 4,641,636 to Cotrel disclose a spinal system which includes a sleeve 30 having a conical part 31. A pressure screw 25 is provided to selectively fix the anchoring members in position on the spinal rod or pin, which has a roughened surface.
U.S. Pat. No. 4,404,967 to Bacal et al. discloses a spinal system having a split or cut sleeve 3 with skew recesses 4 made along the cut. The inner surfaces of recesses 4 constitute bearing surfaces for a pin 2 which protrudes from the spinal rod 1. A conical end of the sleeve fits into a corresponding recess in the hook.
U.S. Pat. No. 4,269,178 to Keene discloses an open back spinal hook having a sleeve which is slidable along the spinal rod and into the hook. A lock nut may then be used to secure the position of the sleeve.